Horn antenna



Aug.` l2, 19474 H. o. PETERSON Er AL 2.,425488 HORN ANTENNA Filed July 3, 1943 Patented Aug. 12, 1947 HORN ANTENNA Harold O. Peterson and Gilbert S. Wickizer,

Riverhead, N. Y., assignors to Radio Corporation of America, a corporation of Delaware Application July 3, 194s, serial No. 493,366

(or 25o- 11) 4 Claims. 1

The present invention relates to antennas and, more particularly, to horn antennas operative in the ultra high frequency spectrum.

In the past, as far as we are aware, antennas of the horn type have been designed for a single frequency. Hence, the simultaneous radiation or reception of two frequencies usually requires two separate horns, Since antennas for ultra high frequencies are usually located as high as possible above the earth the supporting structure requirements are increased by the requirement that a separate horn be used for each separate frequency.

An object of the present invention is to provide a single antenna structure which will radiate or receive two different frequencies each independently of the other.

Another object of the present invention is the provision of an antenna structure for plural frequency use which does not require complex supporting structure.

Still another object of the present invention is the improvement of the directivity of horn radiators.

A further object of the present invention is the provision of a simplied antenna structure for use on a plurality of frequencies.

The foregoing objects, and others which may appear from the following detailed description, are accomplished in a single horn structure by providing a pair of tapered wave guide structures, one for each of the two frequencies and placing the higher frequency wave guide structure within the lower frequency wave guide structure. The combination of the two structures is so arranged that the maximum direction of radiation or reception is directly ahead of the flared portion of the horn.

The present invention will be more fully understood by reference to the following detailed description which is accompanied by a drawing in which there is shown, in perspective, and partly in section, one specific embodiment of the invention.

In the figure there is shown a horn I having a mouth'aperture I I and a throat I2 for radiating or receiving the higher frequency of the pair of frequencies for which the system is designed. I-Iorn I0 is located coaxially within the outer or low frequency horn 20. Horn 20 is provided with a large mouth aperture 2l and a smaller Vthroat aperture 22. The high frequency horn is fed by a wave guide I3 connected to the throat aperture I2 and brought out to the desired transducer equipment. To the throat aperture 22 of the low frequency horn is connected one end of a wave guide structure 23, said wave guide being closed at the other end by a wall 25. In front of wall is located an antenna 24 connected by means of transmission line TL to the desired transducer equipment for the lower frequency. The antenna element 24 is so located in front of wall 25 as to provide a proper termination of the concentric transmission line TL. Since it is dee sirable that the radiating element be rigidly screwed` in a symmetrical position with `respect to the interior partition 26 of wave guide 23, the outer shell of transmission line TL extends inwardly from the upper and lower walls of the guide 23 as indicated at 33 and 34. A desired length of the inner conductor is exposed in the central part to form the radiator 24. In order to electrically free the ends of radiator 2A, the inner extending portions of the outer shell 33, 34, are arranged to have a length of the order of one quarter wavelength. Since the vertical f height of wave guide 23 may. not differ greatly from one half'wavelength, in order to expose a suicient portion of the inner conductor for radiator 24, part of the length lof shell portions 33, 34 may be provided by discs 33' and 34'.

The low frequency wave guide 23 is divided into two ducts over a portion of its length by an inner horizontal dividing wall 26. The ducts extend horizontally from wall to wall of the wave guide 23 and are of' uniform thickness up to the throat aperture 22 of the low frequency horn 20. The horizontal dividing wall 26 is preferably of such thickness that the wave guide I3 associated with the high frequency horn may be accommodated therewithin, thus preventing any irregularities or discontinuities within wave guide 23 which would tend to adversely affect its operation. For the same reason the dividing wall 26 at the end facing antenna 24 is provided with a tapered leading edge 21. The upper and lower ducts within wave guide 23, as has been mentioned, are of uniform thickness at the throat 22. Within horn 20 partitions 28 and 29 are provided to maintain this uniform thickness of the ducts as they approach the mouth of horn 20. At a suitable distance from mouth 2I of horn 20 the partitions 28 and 29 are bent toward each other, as indicated at 30 and 3|,Ito provide a mouth flare so that each duct within horn 20 actually operates as a separate smaller horn, the two operating in parallel. While not so indicated, the open spaces between the vertical edges of horns I0 and 20 may be closed in the plane of mouth 2I by vertical Walls to prevent undesired `wel1 understood in the art.

3 resonance effects from the enclosed cavities formed at either side of horn l0. The higher frequency horn I operates in the usual manner The lower frequency horn operates essentially as two horns in parallel. The two horns are in phase due to their common feed from antenna 24 and the identical lengths Y of the Wave guide feeding the flared portions kof on a single frequency and obtain the sharper directivity feature just mentioned with respectvto the low frequency horns, the higher frequency -horn l0 may be omitted, thus resulting in a single frequency horn Aand associated wave guide divided into a plurality of smaller wave guides and horns energized in a parallel relationship.

f While I have illustrated a particular embodiment of the present invention it should be clearly understood that it is not limited thereto since many modifications may Vloe made in the several elements employed and in their arrangement and it is, therefore, contemplated by the appended claims to cover any such modifications as fall in the sphere and scope of the invention.

We claim: v

l. A dual frequency horn radiator for ultra high frequency electromagnetic waves,V including separatel tapered horns each having mouth and throat apertures, said horns being located in coaxial intertting relationship, means associated with the lower frequency one of said horns for dividing said lower frequency horn into a plurality of separate .horns operating in parallel, -45

wave guide structure and energy transducing means coupled to said throat aperture of said low frequency horn, means for dividing said wave guide structure into a pair of parallel guides, one associated with veach of the said plurality of separate vhorns and wave guide Vstructure coupled to the highfrequency one vof said horns andpassing along said-dividing means to the exteriorof said first kmentioned Wave guide for coupling transducer equipment to said high frequency horn.

2. `A dual frequency horn radiator vforyultra high frequency electromagnetic waves, including separate tapered horns each vhaving mouth and The Vertical directivity of the 10W fre-VK 'throat apertures, said horns being located in coaxial intertting relationship, means associated with the lower frequency one of said horns for dividing said lower frequency horn into a plurality o'f separate horns operating in parallel,

wave guide structureV and energy transducing the high frequency one of said horns and passf ing through Asaid dividing means to the exterior of said `first mentioned wave guide for coupling transducer .equipment to said frequency horn.

3. A tapered horn radiator having mouth and throat apertures, .wave guide and energy transducing means coupled to said throataperture and transverse partitionsV across said horn and,

at least a portion of said waveguide structure -for dividing saidhorn 'into' a plurality Ofpaths 'for electromagnetic energy operating 'in -aY par- Y allel relations-hip, vand a second horn radiator arranged :between a pair of said transverse Dpar-` 'titions in -a coaxial intermitting relationship with said'rst mentioned-horn Vradiator and means for.

coupling said second `horn to energy transducing means. Y c

4. A tapered *horn radiator having mouth and throat apertures, wave guide and energy transducing -means coupled to said throat aperture, transverse partitions being provided across said horn and at least a ,portion of vsaid wave guide structure for dividing said horn into a plurality of paths for electromagnetic energy operating in a parallel relationship, a second 'horn radiator arranged between ,aV pair of said transverse VApartitions in a coaxial interi'itting relationship with said -rst mentioned horn radiator and means for couplingsaidV second horn to energy transducing'means, said last mentioned meansk includ' ing a wave guide structure coupled to thethroat aperture of said high frequency horn 'and passing between the partitionsin said rst mentioned waveguide structure to the exterior thereof. HAROLD O. PETERSQN.y GILBERT S. WICKIZER REFERENCES CITED The `following ,references are of record in the file of this patent: k

UNITED STATES APA'IENTS Number Name .Y Date 1,992,268 Wente Feb. V26, Y1935 2,206,683 Wolff July .2, 194,0 1,750,900 Mintonet al. Mar. 1 8, 1930 2,283,935 King May 26, 1942 

